Emergency release for locking devices



Oct. 16, 1951 w. vENs 2,571,969

EMERGENCY RELEASE FOR LOCKING DEVICES Filed April 25, 1947 2SHEETS-SHEET 1 :llii

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[said Velzsel. BY 4 I Z HIS 47 7 01210?! fiatented Oct. 16, 1951 UNE'EEDSTATES PATrENT OFFICE EMERGENCY RELEASE FOR LOCKING DEVICES IsaiahW.'-Vense1, 'Wilkinsburg, Pa., assignor to Westinghouse Air BrakeCompany, a corporation of Pennsylvania Application'April-ZB,1947,-Serial No. 743,833

9 Claims.

My invention relates to emergency release 'for locking devices, andparticularly. to :emergency releases for locking devices having positiveforcedown features for a locking dog.

Operation of the operating member between its locking and unlockingpositions is controlled by a'lock arrangement usually comprising alocking segment operatively connected with the operating member, and alocking dog movable into and'out of locking engagement With'the lockingsegment.

The locking segment is provided with a shoulder which cooperates withthe locking dog in its looking condition to prevent movement of theoperating member from its looking to its unlocking position until suchtime as the locking dog is withdrawn from the path of movement of theshoul- -der. The locking dog is operated by anysuitable means, such asby an electromagnetorby a mechanically operated time release mechanism,

'andin order to assure that'the locking dog-will bepositioned in lookingengagement with the segmember. When the operating member is moved-through the firstfewdegrees of rotation toward its unlocking position,the projection carriedby the locking segment is .:moved clear of thedepressor member, whereupon. the operating mechanismimmediatelyxsnaps'the lockingpdogout of the pathnof theSegmentshoulderso that the operating member canbe-moved withoutinterruptiontoi its unlockingposition merely by action of the operatorin; throwing the operating member after the unlocked indication has beendisplayed.

-As i customaryinidevices of this character, "means arerequired toprovide for" emergency re- "lease of'the locking 'in the eventbf'aafailureiof the dog operating .mechanisinto operate properly. It-isdesirable thatthe emergency release means: providelioranoperationisimilar :to: that obtained: in. normaloperation, that is, thatafter 0 I effecting anemergency release andobtainingian indication ofthat condition, the. operator will :be ableto throw the:operatingt'member to its .unlocking:positionimerely .by acting .uponthe top- -erating member alone. In'suchcase,therefore,

the emergency releaseimust be eiiective when ment, the looking segmentisprovided'with a projection which cooperates with a i depressor memberconnected with the lockingdog for positively forcing down the lockingdog into locking engagement with the segment when the operating memberis operated from its unlocking to its locking position. The projectionon the locking segment moves in conjunction with the segment and in aportion of the stroke of the-segmenten- .gages a cammed surface formedonthe depressor member to force that memberdownwardly so that its cammedsurface is positioned beneath the projection. With the projection inthis position, upward movement or" the dog required to liftit' out ofthe path of thesegment shoulder will be limited by the engagement of thecammed surface of the member with the underside of the segmentprojection.

In normal operation the parts are'arranged so brought into play toestablish a condition which :remains unchanged during the coursev ofoperationof the opera'ting..member t its unlocking position.

It is an objectiof my invention to provide: novel and improved'emergencyrelease means for locking'devices incorporating positive force-down fea-"tures fcr the locking dog, and which release imeans is arranged whenbrought into operation -to establish a condition which remains un--changed throughout the operation of the operating member to itsunlocking position.

Another object'of my invention is to provide novel and improvedmeans-effective to providean "emergency release for locking devicesarranged to permit operation of "a locking dog to itsunlocking positionwhen the depressor member of the looking dog is in cooperating relationwith a drawdown projection of the locking segment.

Another object of my invention isto provide a "novel and improvedemergencyreleasefor locking devices having positive force-down featuresfor the locking dog.

Another object of my invention is toprovide novel and improved meansfor'obtaining' emer- 1 gency operationof locking devices.

The above-mentioned and other important objects and characteristicfeatures of my invention are obtained by providing the locking devicewith a manually operable'plunger arranged to swing a pivoted depressormember of a locking dog out of engagement with a draw-down projection onthe locking segment and subsequently to force the locking dog out of thepath of movement of the locking segment shoulder.

Other important objects and features of my invention will be apparentfrom the following description.

I shall describe one form of apparatus embodying my invention and shallthen point out the novel features thereof in claims.

Referring to the accompanying drawings, Fig. 1 is a front view with aportion broken away, showing one form of locking device provided with anemergency release embodying my invention. The portion broken away inFig. 1 is shown in section taken on the line A-A of Fig. 3. Fig. 2 is aside view, partially in section, of the locking device illustrated inFig. 1. Fig. 3 is a top view of the locking device shown in Fig. 1, withhousing 60 and certain of the parts omitted. Fig. 4 is a partial viewshowing an arrangement of the parts which form a part of the lockingdevice shown in the drawings. Fig. 5 is a side view showing anarrangement of some of the parts of the emergency release comprising myinvention. Figs. 6 and 7 are side and end views, respectively, of thedepressor member 4|.

In each of the several views similar reference characters refer tosimilar parts.

Referring to the drawings, a locking device having positive force-downfeatures for the looking dog and provided with an emergency releaseembodying my invention is represented, for example, in the form of thewell-known tower indicator comprising a face plate l0, secured as by tapbolts H to a base l2. Plate if! is provided with an opening i3 whichaligns with an opening l4 provided in a supporting member I5 secured bybolts IE to the base i2. shaft I! is mounted in the aligned openings l3and [4 to project past the face plate I!) and has provided thereon anoperating handle l8. A drum type circuit controller is provided foroperating shaft H and comprises a plurality of contact bands |El mountedon insulation carried by shaft 11, and which bands |9 cooperate withpairs of contact fingers 28 (see Fig. 4) secured by means of terminalposts 2| to insulation terminal blocks 22 which in turn are fastened bytap screws 23 to base plate 12. Shaft i7 is also provided with a crankarm 24 formed with an elongated slot 25 in which is mounted a drivingpin 26 carried by a locking member 21. The locking member 21 as shown inFig. l is adapted to be moved into and out of locking engagement with alockable member 28, and when in locking engagement with member 28projects into an opening 29 formed in member 28 to prevent movement ofthe latter member. Shaft I! also is provided with a locking segment 38having a notched or cut-away portion provided with a shoulder 3| whichcooperates with a locking dog 32 pivotally mounted for movement into andout of the path of movement of shoulder 3|.

The operation of dog 32 into and out of the path of shoulder 3| may beeffected in any suitable manner commonly employed in looking devices ofthe type employed in railway signaling and traflic controlling systems.These means may, for example, comprise a time element device of the typeshown in a copending application for Letters Patent of the United StatesSerial No. 734,273, filed March 12, 1947, by Kenneth J. J. McGowan, nowPatent No. 2,520,848, dated August 29, 1950, for Looking Devices, or mayas An operating shown comprise an electromagnet L having two cores 33,each surrounded by a magnetizing coil 34, mounted in parallel spacedrelation on supporting member 15 and connected together at their lowerends by a back-strap 35. An armature 36 carried on an armaturesupporting member 31 pivoted on trunnion screws 38 threaded throughsuitable openings provided in the upper portions of supporting memberI5, is disposed in magnetic relationship with the upper ends of cores 33so as to be attracted to the cores when coils 34 of the electromagnetare energized. The electromagnet L may be provided in the usual mannerwith armature operated contacts comprising a stationary contact element41 carried by a supporting bracket I5 anda movable contact element 48carried by a dependent member 49 attached to armature supporting member31 and arranged to be moved into and out of engagement with contactelement ill according as armature 36 is in its attracted or releasedposition, respectively. It is, of course, obvious that by varying thearrangement of the parts 41 and 48 the contacts formed thereby may bearranged to be open or closed, respectively, according as armature 36 isin its attracted or released position.

Armature supporting member 3! also carries at its opposite end a finger40 to which is secured locking dog 32, the arrangement being such thatwhen electromagnet L is deenergized, dog 32 rotates armature 35counterclockwise (as viewed in Fig. 2) about trunnions 38 to a positionaway from cores 33 with the dog 32 being positioned in the path ofshoulder 3|, but that when electromagnet L is energized, armature 36 isattracted toward cores 33 so that dog 32 is rotated clockwise abouttrunnions 38 to a position clear of the path of shoulder 3|. As will bemade clear hereinafter, the movement of dog 32 to a position clear ofshoulder 3| in response to energization of electromagnet L may berestricted at times by 00- operatin dog and segment elements providingthe positive force-down features for the locking device, but suchmovement will be completed when the dog and segment elements are movedout of cooperating relationship. The cooperating dog and segmentforce-down elements as shown comprise a projection in the form of a lugor pin :34 provided on looking segment 30, and a cooperating depressormember 4| mounted on finger 48 and provided with a cammed surfaceadapted to engage and be driven underneath pin M. Depressor member 4| asshown (see Figs. 6 and 7) has a cam arm 45 carried at the lower end of asupporting leg 45a of member ll, and is beveled at one end so that whendog 32 is positioned clear of shoulder 3| (as shown in Figs. 6 and '7)movement of pin 44 past dog 32 will force the beveled surface of arm 45downwardly to draw down dog 32 into the path of shoulder 3|. The partsare preferably so proportioned that when pin 44 rides on the upperhorizontal surface of arm 45, dog 32 is forced down to approximatelyone-half of the depth of shoulder 3|. When dog 32 occupies its full downposition (illustrated in Fig. 2) the doe. rests on the cut-away portionof segment 30 and the horizontal surface of arm 45 is then disposedunderneath pin 44. With dog 32 in its full down position and member 4|and pin 44 in cooperating relationship any movement of dog 32 upwardlywill be restricted by arm 45 engaging t ing: relationshipwith arm 45 orconversely rm 45is moved'out of 'cooperating'relationship with pin44.

The movement of pin -'44 with relation toarm '45 iseffected' in normaloperation of the locking device, as will be'made clear hereinafter-while movement of arm-c with respect to pin 44-is-requiredfor emergencyoperation of the locking-deviceand in accordance with'my invention isattained'by pivoting-member'l on finger 6B, and by providing meansoperable to swing member-4 l to a' position where cam arm 45 is out ofcooperating relationwith pin 44. Depressormember ll as "shown inFigs. 6and '7'is slotted to'receive-finger 40 to which it is pivotallattachedbyapin-"M passing through aligned openings provided in finger 40and' the-bifurcatedportion-of "member -41 As can be seen inFigp-fi;member 4 I is'pivoted eccentrically so that the weight of "the membercauses it to be biased ina clockwisehirection about pin 42 with cam arm45 normally occupying aposition in which'itis disposed for-cooperatingrelationship with-pin M. The bottom of the slot diagonallyoppositepin-42 is-relieved at an angle (see Fig. 6) which permits member4 l--toberotated counterclockwise about pin 42 to "a position in whicharm *45 clears pin 44,-andin this position of member-4| the relievedbottom of the slot in member'4l will :bear against the bottom of 1finger 46. --A pin '43, as shown in Figs. -6 and 7 preferably is pressedtightly-'into-an opening formed in member iiand rojects at an ang-le -tothe axis'of-finge1' 40. Pin 43 is adapted-to cooperate with anoperatingmember of-an emergency release hereinafter described to :rotate member4! about pin .42 to. a position in :which .arm 45 clears pin 44, andthen subsequently-to lift 'finger 4|] so that dog 32lis withdrawn from 1the path of shoulder 3 I.

.The emergency :release means provided 'for swinging member "4| about:its pivot 42- comprises a manually operabletpmnger E5 slidably'mountedin a supporting bracket 65 secured '.to .the rear of..face plate Iiiwith the plunger, projecting out- ;warclly through an opening formed intheiface plate. The plunger t.65:is'p1'ovided;at;itsouter end with aknob 68 and;istbiasedto"an outer- -most position as by. a coilspringifiaconfined' be- :rtween an upturned leg ofibracketziist-and a sprin-g:collar secured toiplungerfi5 asAby-LaLpin 'I-I. The portion of plunger65 projectingoutwardly :from face plate l'0 is slottedadjacentlto-theface iplate to receivea thin ribbon 73 of metal which hasits ends fastened togetheras by the=usua1 car seal. The sealed ribbonwill 'functiomas-a 'telltale to indicate'that anoperation f plunger 65has been efiected, and .will preventsuch an :operation until-the ribbonis broken and-removed from the slot to permit plunger -t5-toiibemoved:inwardly. iMember:65 carries at its extremein- -mally clear of pin 43of depressor fiL-but'movable when plungerfiia is depressed toengage-..pin 43 to cause rotation of depressor member ik-about itszpivotpin 42 so that-cam arm 45is-oper-ated .clear of pin s l and therelievedportion of-the slot of member lllbears against finger 40 toforce 1 that finger upwardly, thereby moving dog -32 entirely clear ofshoulder 3iof segment 3il.

' The locking 'device alsois provided in the cus-' tomary mannerwithindication :means fo'r in'di- :cating the condition of locking imposedby :the :device upon the operation of shaft ll. 'Ihis means as shown-inFig. 2-comprises-anarcuate ner end an operating member 12 disposed nor-*Visible through a window 5i provideci in -an opeii ing 53formed-iniface plate l ll. Member -SO iS operated byan operatingro'd 54fastened .to looking dog 32 with the arrangement being such thatWhenlocking dog-321s in its'lowermostposition in locking'engagement withsegment 30, arcuate member rotates to its lowermost-position but whenlocking-dog 32 -is operatede-to. or above the previously mentionedposition in which the dog is withdrawn to one-halfof'the depth ofshoulder 3l, rod' 54'drives member 50' to an upperposition in which alegend, such as Unlocked'fis visible through window 52. The pin' 5Iabout which member 50-rotates is supported by-a' member 55 which in turnis-supported from elements SB-secured to or'formed integrally onface-plate HI and disposed. on eitherside of dog 32 to providerestraining surfaces which prevent lateral movement of the dog.

The parts-of the locking device hereinbefore'de scribed are suitablyenclosed by-a housing-6D formed to cover both sides, therear an'dthe'top'of the deviceand provided with an opening 6! through'which a-staple62fastened to face plate [0' projects to provide ahasp fora padlock (notshown) for' locking housing to= the other parts of "the lock device. Thehousing -60 when ren oved' provides access to the working parts of thelocking device.

'The lock device hereinbefore described will operate in "the following'manner: With handle i8 in its extreme left-hand position, asviewed 'inFig. 1, the handle willbe retained-inthis position by the natural biasof the parts-including the weight of locking memberZlsupported fromcrank arm 24. In this position 'of theparts, looking member 21 ispositioned in opening-'29 of lockable member 2 8 so thatthispositionofhandle I8 corresponds to the locking condition of thedevice, and pin 44 carried by segmentfill is disposed immediately abovebut out of-engagement with cam arm 45 of depressor member-4i. With theparts in the positions described and electromagnetL deenergized; dog 32will rest against the notched or cut-away portion of segment 30 so thatthe-dog is disposed inthe'path of movement of shoulder 3|, arcuatemember50 will berotated Tasshown in Fig. 2 to its lowermost positionin whichthe legend Unlocked is obscured, while anotherlegend Locked maybeprovided on the member-"50 to be visible in this condition of theapparatus, or as shown, the latter legend may be omitted from member 50sothat no legendis visible at this time through the window.

I willnow assume that electromagnet L be- "comes energized'in responseto current supplied "to-coils 34 over an energizing circuit (not'shown)When this happens, armature 36 is attracted toward pole pieces 33 torotate armature-supporting -member3l about its trunnion screws 38,thereby causing dog 32 to lift away from the notched portion of segment30. Upward movementof deg- 32 is restricted-howeverat this time sincecamarm -45 of depressor member-4i will engage pin44 carried "by segment39. As previously-mentioned,

the parts of the indication means'areso-propor- This will indicate 'tothe operator member 50 pivoted to rotate about--a pin i I and erationofh-andle W away from-its extreme lefthand position results in pin 44moving to the lelt (as Viewed in Fig. 1) out of engagement with cam arm45, thereby removing the restraint upon the upward movement of dog 32 sothat armature 36 is attracted to its full down position to snap dog 32out of the path of movement of shoulder 3|. This operation will takeplace immediately upon pin 44 disengaging from arm 45 and will result indog 32 being lifted away from the path of shoulder 3| prior to the timethat the shoulder reaches a position of engagement with dog 32, with theresult that handle I 8 can be swung without interruption to its extremeright-hand position to cause operation of the contacts operated by thedrum type controller and to lift locking member 21 out of opening 29 oflockable member 28. With handle l8 in its right-hand position, lockablemember 28, is free to move so that this position of handle I8corresponds to the unlocking condition of the device. The handle will beretained in this position by spring 63 engaging a notch 64 formed in thelower portion of segment 30 (see Fig. 1). It is, of course, obvious thatif the operator should attempt to move handle |8 from its left-hand toits right hand position at a time that dog 32 is disposed in .the pathof shoulder 3|, handle [8 will freely move toward its right-handposition until shoulder 3| abuts against locking dog 32 at whichposition further movement of handle I8 is prevented. The locking dog 32and shoulder 3| therefore cooperate to prevent movement of handle i8 toits right-hand position unless dog 32 is withdrawn from the path ofmovement of shoulder 3| and dog 32 accordingly is positioned in lockingrelationship with segment 30, or is out of such looking relationship,according as the dog is or is not disposed in the path of shoulder 3 Inthis normal operation of handle I8 effective when dog 32 is operated bythe associated dog operating mechanism, it is to be noted that theoperator will not attempt to move handle l8 until after the Unlocked?indication is exhibited through window 52, and that after suchindication is displayed handle |8 may be operated without interruptionto its extreme right-hand position by the operator throwing the handleto its unlocking (right-hand) position. In order to unlock member 28,therefore, the operator is merely required to move handle 18 to itsunlocking (right-hand) position after receiving the Unlocked"indication.

When handle I8 is operated to its right-hand or unlocking position,electromagnet L may be deenergized or not but in either case operationof handle l8 back to its left-hand locking position will result in dog32 assuming its locking relatlonship with segment 3!]. Restoration ofhandle Hi to its left-hand position may be effected only when lockablemember 28 is positioned so that looking member 21 can enter opening 29,and assuming that this condition obtains, handle l8 may then be restoredto its left-hand position by the operator. If electromagnet L isdeenergized at the time handle I8 is restored to its left-hand position,dog 32 will be resting against the upper portion of segment 30 so thatwhen shoulder 3| moves past dog 32, the dog will drop down to restagainst the cutaway portion of the segment and will be positioned forengaging shoulder 3|. If, however, electromagnet L is energized whenhandle I8 is restored to its left-hand position, or if withelectromagnet L deenergized dog 32 should stick in its clear position,then dog 32 will not drop when shoulder 3| moves beyond the dog, but

the dog will be forced down into locking relation-.

ship with segment 3|) by pin 44 engaging cam arm 45 to drive that armdownwardly and under pin 44. This action will usually be suificient tocorrect any sticking action of dog 32 with electromagnet L deenergizedand generally will result in such cases in dog 32 dropping to its fulldown position. In the case where electromagnet 'L is energized, however,the dog 32 will remain in its position half withdrawn from shoulder 3|established by arm 45 engaging pin 44, until electromagnet L becomesdeenergized so that dog 32 drops to its full down position. TheUnlocked" legend of member 50 will of course become obsoured when dog 32operates to its full down position, and this will inform the operatorthat dog 32 is in looking relationship with segment 30.

Under the conditions just described operation of handle l8 from itslocking to its unlocking position will be prevented at all times exceptwhen electromagnet L is energized, and it may be possible that operationof the handle is required at a time when the electromagnet L cannot beenergized as, for example, due to some failure of the parts of itsenergizing circuit. Under these conditions the emergency release meansembodying my invention provides means effective after operation topermit the operator to unlock member 28 merely by moving handle Hi toits unlocking (right-hand) position. Assuming that operation of handlel8 from its left-hand to its right-hand position is desired at a timewhen electromagnet L cannot be energized to operate locking dog 32, theoperator will first break and remove ribbon I3 from the slot of plunger65 so that the plunger is free to be moved inwardly. The operator willnext depress plunger 65 to move operating rod 12 inwardly intoengagement with pin 43 pressed into depressor member 4|. This willrotate member 4| about its pivot 42, arm 45 will be swung out ofcooperating relationship with pin 44, and the relieved bottom of theslot in member 4| will bear against finger 40, thereby forcing thefinger upwardly to drive dog 32 out of the path of shoulder 3|. Theupward movement of dog 32 at this time will not be restrained by arm 45engaging pin 44, consequently the dog 32 will be operated to itsuppermost position in which armature 36 is swung into a positioncorresponding to its attracted position with respect to cores 33, andthe armature and dog will therefore occcupy the positions correspondingto those established when electromagnet L is energized and pin 44 ismoved clear of cam 45. This operation of dog 32 out of lockingrelationship with segment 30 will result in operation of member 58 byrod 54 so that the legend Unlocked is displayed through window 52. Theoperator will hold plunger 65 depressed, and will move handle i8 to itsextreme right-hand unlocking position. Plunger 65 may now be releasedand when the operator does this, plunger 65 will operate to itsoutermost position in response to the bias of spring 69, and operatingrod I2 will disengage from pin 43 so that member 4| will swing back toits biased normal position in which arm 45 is disposed for engaging pin44 when handle I8 is restored to its locking position. Dog 32 will alsodrop into rest against the upper portion of segment 30 and the partswill therefore assume the condition which obtains when electromagnet Lbecomes deenergized after handle 3 is operated to its unlocking positionwith electromagnet L energized. With the parts in the conditiondescribed, the handle |8 may be restored to its left-hand position bythe operator in the manner explained in detail hereinbe- 9 fore inconnection with the. descriptionof the normal operation of thelockingdevice.

It is to be noted that the emergencyrelease means embodyingmyinvention-provides for unlocking member 28mere1y by operating handlel8 to its unlocking position after the Unlocked indication isdisplayedthroughwindow 52. The operation of-the locking device underemergency conditions of operation is therefore identical with theoperation under normalconditions, in that in either case the operatorwill not attemptto move handle l8 until after an Unlock indicationisexhibited, and after such indicationis received the operator obtainsanunlock merely by moving handle l8 withoutinterrup-tion.to its right-handposition. In the-case of emergency operation, the Unlock indication is.provided by the operator depressingplungertE.to its extreme innermostposition before actuating handle l8, so that a conditionis.establishedwhichis maintained by the operator without change whileoperating handle is to unlock member 28.

From the foregoing description it is readily apparent that I haveprovided an emergency release means effective to operate a lockingdogfrom its looking to itsunlooking position during the interval that adepressor member provided on'the locking dog is disposed in a positionto engage a positive draw-down projection provided on the lockingsegment. The emergency release means is arranged to move thedepressor-member out of the path of engagement with the-draw-downprojection and then to. withdraw the locking dog from its lockingposition. The arrangement therefore provides means which makes itpossible to incorporate both a positive draw-down of the locking dog andan emergency release in a locking device.

The emergency release means embodying my invention is highlyadvantageous for use with a locking device having positive force-downfeatures for a locking dog, in that it provides the same type ofoperation of the operating member under both normal and emergencyconditions of operation. The operator may therefore obtain an unlockmerely by moving the operating member after receiving an Unlockindication, and therefore the emergency operation is exactly the same asnormal operation, except for the usual depression of the emergencyrelease plunger required to establish the emergency operation.

Although I have herein shown and described but one form of emergencyrelease for locking devices embodying my invention, it is understoodthat various changes and modifications may be made therein within thescope of the appended claims without departing from the spirit and scopeof my invention.

Having thus described my invention, What I claim is:

1. In a locking device, in combination with a locking dog operable intoand out'of locking engagement with an operating member movable between afirst and a second extreme position only when said locking dog is out ofits locking engagement, two cooperating elements comprising an elementon said operating member and an element on said locking dog, said twoelements being positioned in cooperating relationship in said firstextreme position of said operating member with one of said two elementsprojecting into and obstructing the path traveled by the other elementwhen said locking dog is. operated out of locking engagement with saidoperating member, and means for moving one of said two elements relativeto the otherwhereby toremove said two elementsfromcooperatingrelationship and permit said-dog to be operated out of lockingrelationship. when said operating member occupies its. saidrfirstextreme position. I

2. In a locking device, .alocking .dog operable into and out of lockingrelationship with a'locking segment operablebetween a first and asec-0nd extreme positiononly when said'locking dog is outoflockingrelationship with said segment, two cooperating elements. comprising. a.fi'rstelement on .said locking segmentand a second element onsaidlockingdog, said first element'being positioned in saidfirst extremeposition-of said locking segmentto project into and obstruct the pathtraveled by saidfsecond element whensaid locking dog is operated. out ofits said'locki'ng relationship, and means operable with saidlocking-segment stationary in its said first extreme position for movingoneofsaid. two elements relative to andcle'ar of the othernwh'ereby topermit said dog to be operated out of its said locking relationship,with said locking segment.

3. Ihe combination accordingto claim 2' in which said oneelement-movable relative to-the other is pivoted for rotation into andout ofoooperating. relationship/with said other element, and said' meansfor moving said: one element rotates said one element out of'cooperatingrelationship with. said otherelement.

4. The combination according to .claim 3; in whichsaidmeansrotating'said one element out of cooperatingrelationship withsaidfother element also eflects operation of 'said'locking dog out oflocking relationship with said locking segment.

5. In a locking device, in combination with a locking segment movablebetween two extreme positions and a locking dog operable into and out oflocking engagement with said locking segment for respectively preventingand permitting movement of said segment from one extreme position to theother, a projection on said segment, a cooperating depressor memberpivotally connected with said locking dog and having a cammed surfaceadapted to be driven underneath said projection for drawing down saidlocking dog into locking engagement with said segment, and

means operable for rotating said depressor mem- 1 her out of cooperatingrelationship with said projection whereby to permit said locking dog tobe forced out of locking engagement with said segment.

6. In a locking device, in combination with a locking segment movablebetween two extreme positions and a locking dog operable into and out oflocking engagement with said locking segment for respectively preventingand permitting movement of said segment from one extreme position to theother, a projection on said segment, acooperating depressor memberpivotally connected with said locking dog and having a cammed surfaceadapted to be driven underneath said projection for drawing down saidlocking dog into locking engagement with said segment, and meansoperable for rotating said depressor member out of cooperatingrelationship with said projection and for subsequently forcing saidlocking dog out of locking engagement with said segment.

7. In a locking device having means positively forcing down a lockingdog which cooperates with a shoulder formed on a locking elementoperatively connected with an operating member for preventing movementof said operating member from a first to a second extreme positionunless said locking dog is operated to a position clear of the path ofmovement of said shoulder; said force down means including a projectionon said locking member for cooperating with means carried by saidlocking dog and effective in a given portion of the stroke of saidoperating member to draw down said locking dog into the path of movementof said shoulder, the

combination with such projection of cooperating means comprising amember pivotally mounted on said locking dog for rotation into and outof a position of engagement with said projection and biased into saidengaging position, and means operable for rotating said member againstits bias out of said engaging position to permit said locking dog to beforced clear of said shoul- 'der.

. 8. In a locking device, in combination with a locking segment movablebetween a first and a second position, and a locking dog operable intoand out of locking engagement with said locking segment for respectivelypreventing and permitting movement of said segment from its said firstto its said second position, a projection on said segment, a cooperatingdepressor member pivotally connected with said locking dog and biased toa position to engage said projection when said segment is moved into itssaid first position whereby a portion of said depressor member is drivenbeneath said projection in said first position of said segment, andmeans for rotating said depressor member clear of said projection topermit operation of said locking dog out of locking engagement with saidsegment in its said first position.

9. In a locking device, in combination with a locking segment movablebetween a first and a second position, and a locking dog operable intoand out of locking engagement with said locking segment for respectivelypreventing and permitting movement of said segment from its said firstto its said second position, a projection on said segment, a cooperatingdepressor member pivotally connected with said locking dog and biased toa position to engage said projection when said segment is moved into itssaid first position whereby a portion of said depressor member is drivenbeneath said projection in said first position of said segment, andmeans for rotating said depressor member clear of said projection andfor operating said locking dog out of locking engagement with saidsegment in its said first position.

ISAIAH W. VENSEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

' UNITED STATES PATENTS Number Name Date 1,710,668 Stephenson Apr. 23,1929 2,390,815 Steiner Dec. 11, 1945 2,416,986 Field et a1 Mar. 4, 19472,437,328 McWhirter Mar. 9, 1948

